What exactly is the question here?
Answer:
Problem 1) frequency: 160 heartbeats per minute, period= 0.00625 minutes (or 0.375 seconds)
Problem 2) Runner B has the smallest period
Problem 3) The sound propagates faster via a solid than via air, then the sound of the train will arrive faster via the rails.
Step-by-step explanation:
The frequency of the football player is 160 heartbeats per minute.
The period is (using the equation you showed above):
second problem:
Runner A does 200 loops in 60 minutes so his frequency is:
loops per minute
then the period is: 0.3 minutes (does one loop in 0.3 minutes)
the other runner does 200 loops in 65 minutes, so his frequency is:
loops per minute
then the period is:
Therefore runner B has the smaller period
I think answer is 9.3 after it’s rounded
use the formula a^2 +b^2=c^2
Lets plug in the answer choices and see which one works
A. x = -6
| -6 | < 3
6 < 3
False, so A is not the answer
B. x = -5
| -5 | < 3
5 < 3
False, so B isn't the answer
C. x = -1
| -1 | < 3
1 < 3
True, so C is the answer.
But lets just check D to make sure C is the answer.
D. x = 2
| 2 | < 3
2 < 3
False, so D isn't the answer either.
C is your answer :)